diff toolboxes/FullBNT-1.0.7/bnt/inference/static/@var_elim_inf_engine/marginal_nodes.m @ 0:e9a9cd732c1e tip

first hg version after svn

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolboxes/FullBNT-1.0.7/bnt/inference/static/@var_elim_inf_engine/marginal_nodes.m	Tue Feb 10 15:05:51 2015 +0000
@@ -0,0 +1,79 @@
+function [marginal, loglik] = marginal_nodes(engine, query, add_ev)
+% MARGINAL_NODES Compute the marginal on the specified query nodes (var_elim)
+% [marginal, loglik] = marginal_nodes(engine, query)
+
+if nargin < 3, add_ev = 0; end
+
+assert(length(query)>=1);
+
+evidence = engine.evidence;
+
+bnet = bnet_from_engine(engine);
+ns = bnet.node_sizes;
+n = length(bnet.dag);
+
+onodes = find(~isemptycell(evidence));
+hnodes = find(isemptycell(evidence));
+pot_type = determine_pot_type(bnet, onodes);
+
+% Fold the evidence into the CPTs - this could be done in 'enter_evidence'
+CPT = cell(1,n);
+for i=1:n
+  fam = family(bnet.dag, i);
+  CPT{i} = convert_to_pot(bnet.CPD{bnet.equiv_class(i)}, pot_type, fam(:), evidence);
+end
+
+
+
+sum_over = mysetdiff(1:n, query);
+order = [query sum_over]; % no attempt to optimize this
+
+% Initialize the buckets with the product of the CPTs assigned to them
+B = cell(1,n+1); 
+for b=1:n+1
+  B{b} = mk_initial_pot(pot_type, [], [], [], []);
+end
+for i=1:n
+  b = bucket_num(domain_pot(CPT{i}), order);
+  B{b} = multiply_pots(B{b}, CPT{i});
+end
+
+% Do the marginalization
+sum_over = sum_over(length(sum_over):-1:1); % reverse
+for i=sum_over(:)'
+  % summing over variable i which occurs in bucket j
+  j = bucket_num(i, order);
+  rest = mysetdiff(domain_pot(B{j}), i);
+  % minka
+  if ~isempty(rest)
+    temp = marginalize_pot(B{j}, rest);
+    b = bucket_num(domain_pot(temp), order);
+    %fprintf('summing over bucket %d (var %d), putting result into bucket %d\n', j, i, b);
+    B{b} = multiply_pots(B{b}, temp);
+  end
+end
+
+% Combine all the remaining buckets into one
+result = B{1};
+for i=2:length(query)
+  if ~isempty(domain_pot(B{i}))
+    result = multiply_pots(result, B{i});
+  end
+end
+[result, loglik] = normalize_pot(result);
+
+
+marginal = pot_to_marginal(result);
+% minka: from jtree_inf_engine
+if add_ev
+  bnet = bnet_from_engine(engine);
+  %marginal = add_ev_to_dmarginal(marginal, engine.evidence, bnet.node_sizes);
+  marginal = add_evidence_to_gmarginal(marginal, engine.evidence, bnet.node_sizes, bnet.cnodes);
+end
+
+%%%%%%%%%
+
+function b = bucket_num(domain, order)
+
+b = max(find_equiv_posns(domain, order));
+